KR20170073925A - Light emittng device and light emitting device package including the same - Google Patents

Abstract

An embodiment includes a substrate; And a plurality of first light emitting structures and a plurality of second light emitting structures disposed on the substrate, the first light emitting structures including a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer, Wherein the first light emitting structure is disposed in a first region on the substrate, the second light emitting structure is disposed in a second region around the first region on the substrate, the first light emitting structure emits light in the first wavelength region, And the light emitting structure emits light in a second wavelength range shorter than the first wavelength.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light emitting device and a light emitting device package including the light emitting device.

Embodiments relate to a light emitting device and a light emitting device package including the same.

GaN, and AlGaN are widely used for optoelectronics and electronic devices due to their advantages such as wide and easy bandgap energy.

Particularly, a light emitting device such as a light emitting diode (Ligit Emitting Diode) or a laser diode using a semiconductor material of a 3-5 group or a 2-6 group compound semiconductor has been widely used in various fields such as red, green, blue and ultraviolet It can realize various colors, and it can realize efficient white light by using fluorescent material or color combination. It has low power consumption, semi-permanent lifetime, fast response speed, safety, and environment compared to conventional light sources such as fluorescent lamps and incandescent lamps Affinity.

Therefore, a transmission module of the optical communication means, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, a white light emitting element capable of replacing a fluorescent lamp or an incandescent lamp Diode lighting, automotive headlights, and traffic lights.

1 is a view showing a conventional light emitting device.

A conventional light emitting device 100 includes a light emitting structure 120 including a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 on a substrate 110 made of sapphire or the like The first electrode 150 and the second electrode 160 are disposed on the first conductive semiconductor layer 122 and the second conductive semiconductor layer 126, respectively.

In the light emitting device 100, electrons injected through the first conductive type semiconductor layer 122 and holes injected through the second conductive type semiconductor layer 126 meet to form an energy band inherent to the active layer 124 And emits light having energy determined by the light intensity. The light emitted from the active layer 124 may be different depending on the composition of the material of the active layer 124 and may be blue light, ultraviolet (UV) light, deep ultraviolet light or other wavelength light.

The active layer 124 may have a double heterojunction structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure As shown in FIG.

The above-described conventional light emitting device has the following problems.

Since the substrate and the light emitting structure are different materials, the lattice mismatch is very large and the thermal expansion coefficient difference between them is very large. Therefore, dislocations, melt-backs, cracks, cracks, pits, surface morphology defects and the like may occur.

In order to solve the above-described problems, the buffer layer 115 may be formed as shown in FIG. 1, but the potential may still be formed to deteriorate the quality of the light emitting structure.

The light energy emitted from the active layer may be converted into thermal energy due to the above-described crystal defects and may be released to the outside, thereby lowering the light efficiency.

In addition, the first wavelength region emitted from the light emitting structure 120 excites the phosphor (not shown), and the light of the second wavelength region is emitted from the phosphor, so that the light of the first wavelength region and the light of the second wavelength region White light can be mixed. In this case, a part of light is lost, and it is difficult to control the color temperature and the color rendering index.

Embodiments reduce crystal defects such as dislocations in the growth of a light emitting structure, reduce light loss in a light emitting device package, and easily adjust color temperature and color rendering index.

An embodiment includes a substrate; And a plurality of first light emitting structures and a plurality of second light emitting structures disposed on the substrate, the first light emitting structures including a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer, Wherein the first light emitting structure is disposed in a first region on the substrate, the second light emitting structure is disposed in a second region around the first region on the substrate, the first light emitting structure emits light in the first wavelength region, And the light emitting structure emits light in a second wavelength range shorter than the first wavelength.

A plurality of first light emitting structures may form a photonic crystal stop band to reflect light in the second wavelength region.

The light emitting device may further include a plurality of third light emitting structures disposed on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, And the third light emitting structure emits light in a third wavelength range shorter than the second wavelength.

The light emitting device may be arranged such that the plurality of second light emitting structures form a photonic crystal stop band to reflect light in the third wavelength region.

The diameter of the first light emitting structure may be larger than the diameter of the second light emitting structure.

The diameter of the second light emitting structure may be larger than the diameter of the third light emitting structure.

The pitch of the first light emitting structures may be larger than the pitch of the second light emitting structures.

The pitch of the second light emitting structures may be larger than the pitch of the third light emitting structures.

Each of the light emitting structures may be a rod shape having a nanoscale diameter.

Another embodiment includes a package body; A first electrode layer and a second electrode layer on the package body; And the above-described light emitting device electrically connected to the first electrode pad and the second electrode pad.

The light emitting device according to the embodiments can reduce crystal defects such as dislocations in the growth of a nanoscale light emitting structure, thereby improving the quality. Each of the light emitting structures of the nanoscale emits light in the red, green, and blue wavelength regions, and the light emitted from the light emitting structure is not absorbed by the other light emitting structure due to the arrangement of the light emitting structures, The white light can be realized without the phosphor, so that the light loss of the light emitting device package can be reduced, and the color temperature and the color rendering index can be easily controlled.

1 is a view showing a conventional light emitting device,
2 is a view schematically showing an embodiment of a light emitting device,
FIG. 3 is a view schematically showing a light emitting region of the light emitting device of FIG. 2,
FIG. 4 is a view illustrating light emitting devices in the R, G, and B regions of FIG. 3,
5 is a view showing an interaction of R, G and B light emitting elements,
FIG. 6 is a view showing the arrangement of light emitting structures in the light emitting device of FIG. 2,
7 is a view showing a light emitting device package in which light emitting devices are arranged in a flip chip type.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

In the description of the embodiment according to the present invention, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. In addition, when expressed by upper or lower (on or under), it is possible to include not only the upward direction but also the downward direction based on one element.

2 is a view schematically showing an embodiment of a light emitting device.

In the light emitting device 200 of FIG. 2, the light emitting structure 220 is arranged in a nano rod shape. The active layer 224 and the second conductivity type semiconductor layer 226 are grown around the first conductivity type semiconductor layer 222 partially grown through the mask layer 280. The gap between the nano- The first electrode 265 and the second electrode 275 are disposed on the first conductive semiconductor layer 222 and the gap filling layer 270, respectively.

The details will be described below.

The substrate 210 may be formed of a material suitable for semiconductor material growth or a carrier wafer, may be formed of a material having excellent thermal conductivity, and may include a conductive substrate or an insulating substrate. For example, at least one of sapphire (Al ₂ O ₃ ), SiO ₂ , SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge and Ga ₂ O ₃ can be used.

When the substrate 210 is formed of sapphire or the like and the light emitting structure 220 including GaN or AlGaN is disposed on the substrate 210, lattice mismatch between GaN or AlGaN and sapphire is very large Since the difference in thermal expansion coefficient between them is also very large, dislocations, melt-backs, cracks, pits, and surface morphology defects that deteriorate the crystallinity may occur A buffer layer (not shown) can be formed of AlN or the like.

Although not shown, an undoped GaN layer or an AlGaN layer may be disposed between the buffer layer (not shown) and the light emitting structure 220 to prevent the potentials and the like from being transmitted into the light emitting structure 220.

The light emitting structure 220 includes a first conductive semiconductor layer 222, an active layer 224 and a second conductive semiconductor layer 226. The light emitting structure 220 includes a plurality of nano rod- Thereby forming the light emitting structure 220.

The first conductive semiconductor layer 222 includes a base layer and a protruding structure that is a thin thin film layer on the front surface of the substrate 210 and the protruding structure is grown in the open region between the masks on the base layer .

The protruding structure or the light emitting structure includes a side surface extended from the base layer as shown and a top surface disposed flatly on the top surface and parallel to the surface of the base layer. At this time, the above-described upper surface may be referred to as a flat top.

The cross-section of the protruding structure may be a hexagonal column, a circular or polygonal shape, and each protruding structure may be irregularly arranged in addition to the regular arrangement, and the size or shape of each protruding structure may be equal to or different from each other.

In FIG. 2, the base layer and the protruding structure are divided into dotted lines, but they may be made of the same material, and may be grown before and after using the mask layer 280, respectively.

The mask layer 280 may divide the base layer and the protruding structure, and may also divide each protruding structure. The mask layer 280 may be disposed after the base layer 222a of the first conductivity type semiconductor layer 222 is grown and the protruding structure 222b may be grown to have a smaller cross sectional area.

2, the protruding structure 222b, the active layer 224, and the second conductivity type semiconductor layer 226 in the first conductivity type semiconductor layer 222 are grown after the mask layer 280 is disposed, The active layer 224 and the second conductivity type semiconductor layer 226 may be disposed on the mask layer 280.

2, the mask layer 280 is removed after the protruding structure 222b is grown, and thereafter the active layer 224 and the second conductivity type semiconductor layer 226 are electrically connected to the first conductivity type -Type semiconductor layer 222, which is the same in the following embodiments.

The first conductive semiconductor layer 222 may be formed of a compound semiconductor such as Group III-V or Group II-VI, and may be doped with a first conductive dopant. The first conductive semiconductor layer 222 is a semiconductor material having a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + y? , GaN, InAlGaN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the first conductivity type semiconductor layer 222 is an n-type semiconductor layer, the first conductivity type dopant may include n-type dopants such as Si, Ge, Sn, Se, and Te. The first conductive semiconductor layer 222 may be formed as a single layer or a multilayer, but the present invention is not limited thereto.

The active layer 224 may be grown as a thin film around the protruding structure and the second conductivity type semiconductor layer 226 may be formed as a thin film around the active layer 224 and on the mask layer 280, .

The active layer 224 is disposed between the first conductivity type semiconductor layer 222 and the second conductivity type semiconductor layer 226 and may include a single well structure, a multiple well structure, a single quantum well structure, a multi quantum well (MQW) Well structure, a quantum dot structure, or a quantum wire structure.

InGaN / InGaN, InGaN / InGaN, AlGaN / GaN, InAlGaN / GaN, GaAs (InGaAs), and AlGaN / AlGaN / InGaN / GaN, / AlGaAs, GaP (InGaP) / AlGaP, but is not limited thereto.

The well layer may be formed of a material having an energy band gap smaller than the energy band gap of the barrier layer.

The second conductive semiconductor layer 226 may be formed of a semiconductor compound. The second conductive semiconductor layer 226 may be formed of a compound semiconductor such as a Group III-V or a Group II-VI, and may be doped with a second conductive dopant. The second conductive semiconductor layer 226 may be a semiconductor material having a composition formula of In _x Al _y Ga _{1 -xy} N (0? X? 1, 0? _Y? 1, 0? _X + y? For example, the second conductivity type semiconductor layer 226 may be formed of Al _x Ga _(1-x) N. The second conductivity type semiconductor layer 226 may be formed of Al _x Ga _{y (1-x)} N.

When the second conductivity type semiconductor layer 226 is a p-type semiconductor layer, the second conductivity type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, and Ba. The second conductivity type semiconductor layer 226 may be formed as a single layer or a multilayer, but is not limited thereto.

Although not shown, an electron blocking layer may be disposed between the active layer 224 and the second conductive semiconductor layer 226. The electron blocking layer may have a superlattice structure. For example, the superlattice may include AlGaN doped with a second conductive dopant, and GaN having a different composition ratio of aluminum may be formed as a layer And a plurality of these may be alternately arranged.

A gap filling layer 270 may be disposed in each of the gaps, and the gap filling layer 270 may include a metal layer and may be formed by electroplating electroplating).

The gap filling layer 270 may be made of a conductive material so as to stably support the light emitting structure 220 and to supply holes or electrons uniformly to the entire region of the second conductivity type semiconductor layer 226.

The first electrode 265 and the second electrode 275 may be disposed on the first conductive semiconductor layer 222 and the gap filling layer 270, respectively. The first electrode 265 and the second electrode 275 may include at least one of aluminum (Al), titanium (Ti), chrome (Cr), nickel (Ni), copper (Cu) Or a multi-layer structure.

It is difficult to stably arrange the electrodes due to the aspect ratio of the light emitting structure 220 when the electrodes are formed on the light emitting structure 220 having the nanoscale diameter and when the electrodes are formed on the upper surface of the light emitting structure 220, The conductive layer may be formed of a gap filling layer 270 by an electroplating method or the like to stably support the light emitting structure 220. [

In the light emitting device 200 of FIG. 2, the light emitting structure 220 is grown in the shape of a nano-rod, and the occurrence of the potentials and the like described above can be reduced. Although the conventional nano-rod-shaped light emitting structure 220 may reduce crystal defects such as dislocation, the light of the first wavelength range emitted from each nano-rod-shaped light emitting structure 220 excites the phosphor, The light of the second wavelength range is emitted, so that some light is lost and it is difficult to control the color temperature and the color rendering index.

Accordingly, the nano-rod-shaped light emitting structure 220 may include the first to third light emitting structures that emit light in different regions.

Fig. 3 is a diagram schematically showing a light emitting region of the light emitting device of Fig. 2;

That is, the wavelength regions of the light emitted from the light emitting structures 220 to nano rods in FIG. 2 may be different from each other. In FIG. 3, the red region in the center region R, which is the first region, A light emitting structure for emitting light in the blue wavelength region is disposed in the edge region B of the third region, and a light emitting structure for emitting light in the green wavelength region is disposed in the middle G region, which is the second region, The structure can be arranged.

4A to 4C are views showing light emitting devices of the R, G, and B regions of FIG.

4A, the first light emitting structure Rod _R is disposed in the R region, and the pitch P ₁ between the first light emitting structures Rod _R is defined. In the G region in FIG. 4B, is disposed (Rod _G), respectively of, and the second light-emitting structure (Rod _G), the pitch (P ₂₎ defined between in Figure 4c B area and the is disposed three light emitting structure (Rod _B), each And the pitch P ₃ between the third light emitting structures (Rod _B ) is defined.

In this embodiment, for example, light in a red wavelength range is emitted in the first light emitting structure (Rod _R ) in the first region, light in the green wavelength region is emitted in the second light emitting structure (Rod _G ) In the light emitting structure (Rod _B ), light in the blue wavelength region can be emitted.

5 is a view showing the interaction of R, G, and B light emitting devices.

The light in the red wavelength region emitted from the first light emitting structure Rod _R of the first region can be transmitted to the outside without being absorbed by the second light emitting structure Rod _G and the third light emitting structure Rod _B . The light in the green wavelength region emitted from the second light emitting structure Rod _G can be emitted to the outside without being absorbed by the third light emitting structure Rod _B.

At this time, the third light-emitting structure light of the blue wavelength region emitted from the (Rod _B) is first may be reflected no 2 not absorbed by the semiconductor layers (Rod _G), also the second emitted from the light emitting structure (Rod _G) green wavelength The light of the region can be reflected without being absorbed by the first light emitting structure (Rod _R ).

For the above-mentioned operation, the first light emitting structures Rod _R may be arranged to form a photonic crystal stop band so as to reflect the green light which is the light in the second wavelength region. In addition, the second light emitting structures Rod _G may be arranged to form a photonic crystal stop band so as to reflect blue light, which is the light in the third wavelength range.

6 is a view showing the arrangement of light emitting structures in the light emitting device of FIG.

Generally, the larger the distance or pitch between adjacent light emitting structures, the more photonic crystal stop band that reflects a longer wavelength can be formed.

Therefore, the pitch P ₁ between the first light emitting structures Rod _R of the first region may be greater than the pitch P ₂ between the second light emitting structures Rod _{G of} the second region, The pitch P ₂ between the second light emitting structures Rod _G may be larger than the pitch P ₃ between the third light emitting structures Rod _B of the third region.

The diameter R ₁ of the first light emitting structure Rod _R in the first region may be greater than the diameter R ₂ of the second light emitting structure Rod _{G in} the second region, The diameter R ₂ of the light emitting structure Rod _G may be larger than the diameter R ₃ of the third light emitting structure Rod _B of the third region.

And, the distance between the first region of the first light-emitting structure (Rod _R) and the second light-emitting structure (Rod _G) of the second area (d ₁₎ of the second light-emitting structure (Rod _G) and the third of the second region And the distance d ₂ between the third light emitting structures (Rod _B ) of the region.

Generally, the larger the interval between the light emitting structures, the more the indium is contained in the light emitting structure, especially, the active layer, so that the longer wavelength light can be emitted.

The light emitting device according to the above-described embodiments can reduce crystal defects such as dislocations in the growth of a nanoscale light emitting structure, thereby improving quality. Each of the light emitting structures of the nanoscale emits light in the red, green, and blue wavelength regions, and the light emitted from the light emitting structure is not absorbed by the other light emitting structure due to the arrangement of the light emitting structures, The white light can be realized without the phosphor, so that the light loss of the light emitting device package can be reduced, and the color temperature and the color rendering index can be easily controlled.

7 is a view showing a light emitting device package in which light emitting devices are arranged in a flip chip type.

The first electrode pad 721 and the second electrode pad 722 may be fixed to the supporting substrate 700 having the cavity through the bonding layer 710. [ In FIG. 7, the side walls of the cavity formed in the support substrate 700 are disposed at an obtuse angle with the bottom surface, but may be disposed at a right angle.

2, the first electrode 265 and the second electrode 275 of the light emitting device 200 may be arranged in the form of a flip chip, The first electrode pad 721 and the second electrode pad 722, respectively.

At this time, the second electrode 265 may be extended to contact the second electrode pad 722. This structure does not require a separate bump for coupling between the electrode and the electrode pad, and the light emitted from the light emitting structure 220 can travel in the upward direction of FIG.

The light emitting device package may have a configuration such as a molding part in addition to the above-described configuration.

The light emitting device package may be mounted as one or a plurality of light emitting devices according to the embodiments described above, but the present invention is not limited thereto.

The light emitting device to the light emitting device package described above can be used as a light source of an illumination system, for example, a backlight unit of a video display device and a lighting device.

When used as a backlight unit of an image display apparatus, it can be used as a backlight unit of an edge type or as a direct-type backlight unit, and can be used as a light source of a register or a ball type when used in a lighting apparatus.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

100, 200: light emitting element 115: buffer layer
110, 210: substrate 120, 220: light emitting structure
265: first electrode 270: gap filling layer
275: second electrode 280: mask layer
700: Support substrate

Claims (10)

Board; And
A plurality of first light emitting structures and a plurality of second light emitting structures disposed on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer,
Wherein the first light emitting structure is disposed in a first region on the substrate and the second light emitting structure is disposed in a second region around the first region on the substrate, And the second light emitting structure emits light of a second wavelength range shorter than the first wavelength. The method according to claim 1,
Wherein the plurality of first light emitting structures are arranged to form a photonic crystal stop band so as to reflect light in the second wavelength region. The method according to claim 1,
Further comprising a plurality of third light emitting structures disposed on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer,
Wherein the third light emitting structure is disposed in a third region in the second region on the substrate, and the third light emitting structure emits light in a third wavelength region having a shorter wavelength than the second wavelength. The method according to claim 1,
Wherein the plurality of second light emitting structures are arranged to form a photonic crystal stop band so as to reflect light in the third wavelength region. 5. The method according to any one of claims 1 to 4,
Wherein a diameter of the first light emitting structure is larger than a diameter of the second light emitting structure. The method according to claim 3 or 4,
Wherein a diameter of the second light emitting structure is larger than a diameter of the third light emitting structure. 5. The method according to any one of claims 1 to 4,
Wherein a pitch of the first light emitting structures is larger than a pitch of the second light emitting structures. The method according to claim 3 or 4,
Wherein the pitch of the second light emitting structures is larger than the pitch of the third light emitting structures. 5. The method according to any one of claims 1 to 4,
Wherein each of the light emitting structures is a rod shape having a nanoscale diameter. A support substrate;
A first electrode layer and a second electrode layer on the supporting substrate; And
The light emitting device package according to any one of claims 1 to 4, which is electrically connected to the first electrode pad and the second electrode pad.

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